Abstract: A device for filtering dust from air drawn by apparatus from a factory shop or building, for example a steelmaking shop, including a plurality of dust extractors which have a total capacity at least equal to the air throughput of the drawn air. The extractors have regulators by which they can be regulated individually or in groups. Preferably each extractor is associated with an individual dust extractor and also each extractor preferably has its own individual cleaning system. The extractors are preferably of the dry filter bag type.

Abstract: A hood-like chamber over a converter vessel for refining pig iron, affords the collection of exhaust gases from the vessel and the direction of the gases into an exhaust gas line. The chamber is formed by a top wall containing an opening into the exhaust gas line, and side walls extend downwardly from the top wall. The lower ends of the side walls are located above the bottom of the vessel. A flange extends inwardly from the lower end of the side walls into contact with a collar extending radially outwardly from a support ring encircling the vessel. A seal can be provided between the flange and the collar to prevent the passage of air between them into the chamber. Alternatively, a gap can be left between the flange and the collar to admit a certain amount of secondary air into the chamber.

Abstract: A method for treating waste gases which are emitted from metallurgic refining methods wherein the gas is collected, cooled, cleaned and stored, and wherein the gas is removed from the refining method and treated under an excess pressure which pressure results from the refinery gas pressure. An apparatus for carrying out the method comprising a metallurgic vessel contained in a pressure vessel which is connected to a waste gas cooler and a dust separator is disclosed.